Stabilization of strandboard by impregnating low molecular weight phenol formaldehyde resins and butanetetracarboxylic acid

Oriented strandboard(OSB) swells in water in part due to the release of compressed wood strands that are not bonded during hot pressing. This dimensional swelling could be ameliorated by impregnating wood cellulose and lignin structures with functional chemicals such as butanetetracarboxylic acid (BTCA) and low molecular weight (MW) phenol-formaldehyde (PF) resins.; This study showed that impregnating low loadings of BTCA in southern pine (SP) strands improved the dimensional stability (less swelling) of strandboards based on reversible and irreversible swelling, along with some decrease in mechanical strength properties. The BTCA impregnation improved the wood strand dimensional stability more in the radial direction on the basis of both irreversible and reversible swelling. This study also showed that impregnating low loadings of low MW PF resins into SP strands improved the dimensional stability of strandboard based on irreversible and reversible swelling without decreasing the mechanical strength properties. The PF resin impregnation improved the wood strand dimensional stability selectively in the tangential direction on the basis of irreversible swelling.; The flow path of PF resin in SP was through the ray tracheids. The diffusion of PF resin into the cell wall is probably via the primary wall and rays and not via the warty layer or S3 layer of the cell wall. The PF resins impregnated in ray tracheids tended to form interlocks that restrain the dimensional changes of treated SP strands in the tangential direction. PF resins in ray tracheids probably fortified the ray tracheids and restrained the strand dimensional changes in the radial direction.